// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <math.h>
#include <stdint.h>
#include <stdlib.h>
#include <limits>

#include "include/v8config.h"

#include "src/base/bits.h"
#include "src/base/ieee754.h"
#include "src/memcopy.h"
#include "src/utils.h"
#include "src/v8memory.h"
#include "src/wasm/wasm-external-refs.h"

namespace v8 {
namespace internal {
    namespace wasm {

        void f32_trunc_wrapper(Address data)
        {
            WriteUnalignedValue<float>(data, truncf(ReadUnalignedValue<float>(data)));
        }

        void f32_floor_wrapper(Address data)
        {
            WriteUnalignedValue<float>(data, floorf(ReadUnalignedValue<float>(data)));
        }

        void f32_ceil_wrapper(Address data)
        {
            WriteUnalignedValue<float>(data, ceilf(ReadUnalignedValue<float>(data)));
        }

        void f32_nearest_int_wrapper(Address data)
        {
            WriteUnalignedValue<float>(data, nearbyintf(ReadUnalignedValue<float>(data)));
        }

        void f64_trunc_wrapper(Address data)
        {
            WriteUnalignedValue<double>(data, trunc(ReadUnalignedValue<double>(data)));
        }

        void f64_floor_wrapper(Address data)
        {
            WriteUnalignedValue<double>(data, floor(ReadUnalignedValue<double>(data)));
        }

        void f64_ceil_wrapper(Address data)
        {
            WriteUnalignedValue<double>(data, ceil(ReadUnalignedValue<double>(data)));
        }

        void f64_nearest_int_wrapper(Address data)
        {
            WriteUnalignedValue<double>(data,
                nearbyint(ReadUnalignedValue<double>(data)));
        }

        void int64_to_float32_wrapper(Address data)
        {
            int64_t input = ReadUnalignedValue<int64_t>(data);
            WriteUnalignedValue<float>(data, static_cast<float>(input));
        }

        void uint64_to_float32_wrapper(Address data)
        {
            uint64_t input = ReadUnalignedValue<uint64_t>(data);
            float result = static_cast<float>(input);

#if V8_CC_MSVC
            // With MSVC we use static_cast<float>(uint32_t) instead of
            // static_cast<float>(uint64_t) to achieve round-to-nearest-ties-even
            // semantics. The idea is to calculate
            // static_cast<float>(high_word) * 2^32 + static_cast<float>(low_word). To
            // achieve proper rounding in all cases we have to adjust the high_word
            // with a "rounding bit" sometimes. The rounding bit is stored in the LSB of
            // the high_word if the low_word may affect the rounding of the high_word.
            uint32_t low_word = static_cast<uint32_t>(input & 0xFFFFFFFF);
            uint32_t high_word = static_cast<uint32_t>(input >> 32);

            float shift = static_cast<float>(1ull << 32);
            // If the MSB of the high_word is set, then we make space for a rounding bit.
            if (high_word < 0x80000000) {
                high_word <<= 1;
                shift = static_cast<float>(1ull << 31);
            }

            if ((high_word & 0xFE000000) && low_word) {
                // Set the rounding bit.
                high_word |= 1;
            }

            result = static_cast<float>(high_word);
            result *= shift;
            result += static_cast<float>(low_word);
#endif

            WriteUnalignedValue<float>(data, result);
        }

        void int64_to_float64_wrapper(Address data)
        {
            int64_t input = ReadUnalignedValue<int64_t>(data);
            WriteUnalignedValue<double>(data, static_cast<double>(input));
        }

        void uint64_to_float64_wrapper(Address data)
        {
            uint64_t input = ReadUnalignedValue<uint64_t>(data);
            double result = static_cast<double>(input);

#if V8_CC_MSVC
            // With MSVC we use static_cast<double>(uint32_t) instead of
            // static_cast<double>(uint64_t) to achieve round-to-nearest-ties-even
            // semantics. The idea is to calculate
            // static_cast<double>(high_word) * 2^32 + static_cast<double>(low_word).
            uint32_t low_word = static_cast<uint32_t>(input & 0xFFFFFFFF);
            uint32_t high_word = static_cast<uint32_t>(input >> 32);

            double shift = static_cast<double>(1ull << 32);

            result = static_cast<double>(high_word);
            result *= shift;
            result += static_cast<double>(low_word);
#endif

            WriteUnalignedValue<double>(data, result);
        }

        int32_t float32_to_int64_wrapper(Address data)
        {
            // We use "<" here to check the upper bound because of rounding problems: With
            // "<=" some inputs would be considered within int64 range which are actually
            // not within int64 range.
            float input = ReadUnalignedValue<float>(data);
            if (input >= static_cast<float>(std::numeric_limits<int64_t>::min()) && input < static_cast<float>(std::numeric_limits<int64_t>::max())) {
                WriteUnalignedValue<int64_t>(data, static_cast<int64_t>(input));
                return 1;
            }
            return 0;
        }

        int32_t float32_to_uint64_wrapper(Address data)
        {
            float input = ReadUnalignedValue<float>(data);
            // We use "<" here to check the upper bound because of rounding problems: With
            // "<=" some inputs would be considered within uint64 range which are actually
            // not within uint64 range.
            if (input > -1.0 && input < static_cast<float>(std::numeric_limits<uint64_t>::max())) {
                WriteUnalignedValue<uint64_t>(data, static_cast<uint64_t>(input));
                return 1;
            }
            return 0;
        }

        int32_t float64_to_int64_wrapper(Address data)
        {
            // We use "<" here to check the upper bound because of rounding problems: With
            // "<=" some inputs would be considered within int64 range which are actually
            // not within int64 range.
            double input = ReadUnalignedValue<double>(data);
            if (input >= static_cast<double>(std::numeric_limits<int64_t>::min()) && input < static_cast<double>(std::numeric_limits<int64_t>::max())) {
                WriteUnalignedValue<int64_t>(data, static_cast<int64_t>(input));
                return 1;
            }
            return 0;
        }

        int32_t float64_to_uint64_wrapper(Address data)
        {
            // We use "<" here to check the upper bound because of rounding problems: With
            // "<=" some inputs would be considered within uint64 range which are actually
            // not within uint64 range.
            double input = ReadUnalignedValue<double>(data);
            if (input > -1.0 && input < static_cast<double>(std::numeric_limits<uint64_t>::max())) {
                WriteUnalignedValue<uint64_t>(data, static_cast<uint64_t>(input));
                return 1;
            }
            return 0;
        }

        int32_t int64_div_wrapper(Address data)
        {
            int64_t dividend = ReadUnalignedValue<int64_t>(data);
            int64_t divisor = ReadUnalignedValue<int64_t>(data + sizeof(dividend));
            if (divisor == 0) {
                return 0;
            }
            if (divisor == -1 && dividend == std::numeric_limits<int64_t>::min()) {
                return -1;
            }
            WriteUnalignedValue<int64_t>(data, dividend / divisor);
            return 1;
        }

        int32_t int64_mod_wrapper(Address data)
        {
            int64_t dividend = ReadUnalignedValue<int64_t>(data);
            int64_t divisor = ReadUnalignedValue<int64_t>(data + sizeof(dividend));
            if (divisor == 0) {
                return 0;
            }
            WriteUnalignedValue<int64_t>(data, dividend % divisor);
            return 1;
        }

        int32_t uint64_div_wrapper(Address data)
        {
            uint64_t dividend = ReadUnalignedValue<uint64_t>(data);
            uint64_t divisor = ReadUnalignedValue<uint64_t>(data + sizeof(dividend));
            if (divisor == 0) {
                return 0;
            }
            WriteUnalignedValue<uint64_t>(data, dividend / divisor);
            return 1;
        }

        int32_t uint64_mod_wrapper(Address data)
        {
            uint64_t dividend = ReadUnalignedValue<uint64_t>(data);
            uint64_t divisor = ReadUnalignedValue<uint64_t>(data + sizeof(dividend));
            if (divisor == 0) {
                return 0;
            }
            WriteUnalignedValue<uint64_t>(data, dividend % divisor);
            return 1;
        }

        uint32_t word32_ctz_wrapper(Address data)
        {
            return base::bits::CountTrailingZeros(ReadUnalignedValue<uint32_t>(data));
        }

        uint32_t word64_ctz_wrapper(Address data)
        {
            return base::bits::CountTrailingZeros(ReadUnalignedValue<uint64_t>(data));
        }

        uint32_t word32_popcnt_wrapper(Address data)
        {
            return base::bits::CountPopulation(ReadUnalignedValue<uint32_t>(data));
        }

        uint32_t word64_popcnt_wrapper(Address data)
        {
            return base::bits::CountPopulation(ReadUnalignedValue<uint64_t>(data));
        }

        uint32_t word32_rol_wrapper(Address data)
        {
            uint32_t input = ReadUnalignedValue<uint32_t>(data);
            uint32_t shift = ReadUnalignedValue<uint32_t>(data + sizeof(input)) & 31;
            return (input << shift) | (input >> ((32 - shift) & 31));
        }

        uint32_t word32_ror_wrapper(Address data)
        {
            uint32_t input = ReadUnalignedValue<uint32_t>(data);
            uint32_t shift = ReadUnalignedValue<uint32_t>(data + sizeof(input)) & 31;
            return (input >> shift) | (input << ((32 - shift) & 31));
        }

        void float64_pow_wrapper(Address data)
        {
            double x = ReadUnalignedValue<double>(data);
            double y = ReadUnalignedValue<double>(data + sizeof(x));
            WriteUnalignedValue<double>(data, base::ieee754::pow(x, y));
        }

        void memory_copy_wrapper(Address dst, Address src, uint32_t size)
        {
            // Use explicit forward and backward copy to match the required semantics for
            // the memory.copy instruction. It is assumed that the caller of this
            // function has already performed bounds checks, so {src + size} and
            // {dst + size} should not overflow.
            DCHECK(src + size >= src && dst + size >= dst);
            uint8_t* dst8 = reinterpret_cast<uint8_t*>(dst);
            uint8_t* src8 = reinterpret_cast<uint8_t*>(src);
            if (src < dst && src + size > dst && dst + size > src) {
                dst8 += size - 1;
                src8 += size - 1;
                for (; size > 0; size--) {
                    *dst8-- = *src8--;
                }
            } else {
                for (; size > 0; size--) {
                    *dst8++ = *src8++;
                }
            }
        }

        void memory_fill_wrapper(Address dst, uint32_t value, uint32_t size)
        {
            // Use an explicit forward copy to match the required semantics for the
            // memory.fill instruction. It is assumed that the caller of this function
            // has already performed bounds checks, so {dst + size} should not overflow.
            DCHECK(dst + size >= dst);
            uint8_t* dst8 = reinterpret_cast<uint8_t*>(dst);
            uint8_t value8 = static_cast<uint8_t>(value);
            for (; size > 0; size--) {
                *dst8++ = value8;
            }
        }

        static WasmTrapCallbackForTesting wasm_trap_callback_for_testing = nullptr;

        void set_trap_callback_for_testing(WasmTrapCallbackForTesting callback)
        {
            wasm_trap_callback_for_testing = callback;
        }

        void call_trap_callback_for_testing()
        {
            if (wasm_trap_callback_for_testing) {
                wasm_trap_callback_for_testing();
            }
        }

    } // namespace wasm
} // namespace internal
} // namespace v8
